Stopping medication abruptly raises heart risk

A DISCOVERY involving Irish researchers could help fine-tune how medication is managed in patients who have undergone a stenting procedure.

By analysing blood samples, the study found that when a patient stops taking a blood-thinning medication a year after a stent is put in, platelet cells in their blood may exhibit a spike of stickiness within a few weeks and increase the risk of a heart attack.

Researcher Dermot Kenny, professor of cardiovascular biology at the Royal College of Surgeons in Ireland, explained that when a stent is inserted into an artery to help keep blood flowing through it, the patient is at higher risk of forming a clot, which could lead to a heart attack or stroke.

So the patients are typically recommended to take two types of medication for a year – aspirin and a drug called Plavix – to stop blood platelets clumping together.

However, if patients suddenly stop taking Plavix after that year, there’s a slight but observable increased risk of heart attack, according to Prof Kenny.

“There’s a clustering of heart attacks after about one month,” he said, although he stressed that this affects a small number of patients.

The new study measured various aspects of platelet stickiness in 32 patients at a number of time points before and after the medication was stopped, explained Prof Kenny.

“At one month, in about two-thirds of the patients there was a transient period of what we call hyperactivity in the platelets, and that corresponds exactly to when you see this clustering,” he said.

“When the medication is withdrawn you would expect their platelets to return to a more sticky state, but what we found was that in a percentage of them there was a spike in activity after one month.”

The discovery could help fine-tune how patients withdraw from the medication, and Prof Kenny advised patients to talk to their cardiologists.

“Our research suggests that patients should be weaned off these drugs over time rather than have them stopped abruptly as is done now, in order to prevent the increased risk of heart attack.

“But it’s not going to be uniform for everybody, and patients shouldn’t discontinue the medication without discussing with their cardiologist how they are going to do it.”

Prof Kenny carried out the research with collaborators in Belgium and in Beaumont Hospital, including consultant cardiologist Prof David Foley. The paper was published in the Journal of Thrombosis and Haemostasis.